Erectile dysfunction is considered a common disorder affecting approximately 10% of men of any age. The incidence of this dysfunction, however, increases dramatically with age. By definition, erectile dysfunction is the inability to attain and maintain the erection of the penis a sufficient time to permit satisfactory sexual intercourse. The cause of erectile dysfunction may be of psychogenic, organic, iatrogenic, or hormonal origin. Psychogenic based erectile dysfunction may occur in patients under age 35 due to psychological disorders such as depression, anxiety, stress, performance anxiety etc. Organic based dysfunction may occur in older patients due to a vascular, cavernosal or neurological disease such as atherosclerosis, hypertension, smoking, diabetes, spinal injury, multiple sclerosis etc. Iatrogenic based dysfunction mainly appears after the administration of drugs or the performance of medical/surgical procedures. It has been reported that over 130 drugs can cause erectile dysfunction as a side effect, including for example such drugs as antihypertensives (e.g. β-blockers and diuretics) and hypoglycemics. Hormonal based dysfunction mainly occurs due to changes in testosterone levels or other hormones or chemical messengers.
The cause of impotence commonly determines the treatment of penile erectile dysfunction, with the ultimate goal of recovering sexual activity. Treatment may involve procedures such as psychotherapy, vascular surgery, or prosthetic surgery. Alternatively, therapeutic agents may be selected for pharmacotherapy which can be administered orally, topically, intra-urethrally or injected intracavernously (EP 702555; EP 249194; EP 459377; U.S. Pat. Nos. 5,242,391; 5,474,535; 5,492,911; 5,576,290; 5,658,936; 5,698,589; and 5,842,039). In certain circumstances, specific devices may be used in treatment such as a vacuum cylinder device. The cause of the dysfunction may determine the therapeutic approach of choice.
Where therapeutic agents are used, different routes of administration of the agent to the subject are associated with certain disadvantages. For example, the intra-urethral route of administration may cause side effects for both patient and partner because a portion of the administered drug remains in the urethra and, thus, can be transmitted to the partner during intercourse. The self-injection route during intracaverneous administration has disadvantages associated with lack of spontaneity and unpleasant and sometimes pathological side effects and suffers from a high drop-out rate of the user population. Although oral administration is a convenient and attractive approach of therapy, this approach is open to abuse by patients without erectile dysfunction, but who would try an oral formulation for improving performance. The topical route relying on a gel, cream, or ointment lacks dose precision at the site of application, namely the penis skin. Transdermal delivery methods have been utilized for the systemic treatment of certain disorders as in U.S. Pat. Nos. 5,152,997; 4,812,313; 4,954,344; and 5,302,395. Several trials to optimize drug delivery to the penis by the transdermal route leading to successful sexual intercourse have resulted in developing a variety of transdermal drug delivery systems. There are however problems associated with these systems relating to the change in the surface texture of the penis and the implications of friction of penis against vagina.
Where attempts have been made to employ transdermal delivery devices for the treatment of erectile dysfunction, a rather complicated vasodilator delivery system has been developed (U.S. Pat. No. 5,333,621) which is complex in design and inconvenient to use. The system consists of three or two adhesive layers, which are adhered inside a condom. Upon use, the three layer patch is adhered to the penis skin after applying pressure to the condom.
Another transdermal delivery device for the treatment of male impotence is described in U.S. Pat. No. 5,741,511. The device is in the form of a cylinder matrix type or a multi-reservoir patch applied to the glans penis. Even in this case, to obtain the maximum of the desired effect the patch has to be accompanied by a support and rings attached to the penis. After achieving enough erection, the patch and support are removed while the rings remain during the intercourse. This device is unpleasant and inconvenient for both the patient and his partner.
Still another transdermal delivery device (patch) containing prostaglandin for the treatment of any pathological condition (e.g. peripheral arterial occlusive disease) is described in U.S. Pat. No. 5,480,648. The patch described in '648 consists of a pressure sensitive adhesive containing the active and other additives, laminated onto a backing film. However, the drug release profile of this patch disclosed long term delivery which is unsuited for the treatment of erectile dysfunction because an effective dose of an active agent is required over a short period of time prior to intercourse so as to provide a positive response (rigid tumescence of penis).
Therefore, there is a need to develop a system and method for the treatment of erectile dysfunction that is simple, safe, convenient and painless to use, but not open to abuse and that delivers an effective “therapeutic dose” to the penis over a short period of time and is applied directly to the penis surface without using any additional support, and eventually enables the patient to achieve normal sexual activity.